Timcodar dimesylate is a new chemical entity developed to promote neuronal growth. The primary objective of this protocol is to evaluate the safety and tolerability of six different doses of timcodar dimesylate administered over twenty-eight days to patients with diabetic polyneuropathy. The secondary objective is the assessment of the pharmacokinetics of the drug and exploration of any relationship between the study drug and nerve function. The latter will be assessed using nerve conduction studies and quantitative sensory testing. The patient population will consist of seventy-two patients with Type I or II diabetes who have a sensory polyneuropathy. The double-blind, randomized, placebo-controlled three-tier study will be conducted on an outpatient basis at seven to ten study sites. Patients will be followed using measurements of the physical and neurological examinations as well as clinical laboratory findings. The primary purpose of the study is to evaluate the safety and tolerability of six different doses of timcodar dimesylate. At the present time, no information is available concerning the efficacy of the study drug. If the drug proves to be beneficial, timcodar dimesylate would rise to the top of potential treatments for stabilizing and possibly reversing the complications of diabetic neuropathy.